1. Field of the Invention
The present invention relates to a work vehicle comprising a vehicle body frame extending in the fore/aft direction, a passenger's section included in the vehicle body frame, a driver's seat disposed forwardly of the passenger's section, and a drive unit under which the vehicle body frame is disposed, the drive unit having an engine.
2. Description of the Related Art
The work vehicle of the above-noted type is conveniently used not only for transportation of construction material or the like, but also for transportation of passengers. And, in such work vehicle, if the drive unit is disposed under the vehicle body frame, this can eliminate the need to provide a space on the vehicle body frame for disposing the drive unit. So, there is obtained the advantageous possibility of effectively utilizing the space on the vehicle body frame which would tend otherwise to be restricted to ensure a large space for passengers. A work vehicle employing such construction is known from the U.S. Pat. No. 6,994,388 (see FIGS. 2A, 2B, FIGS. 3A, 3B). With this work vehicle, another seat can be disposed rearwardly of the driver's seat and a rear portion of the vehicle body frame, thee is disposed a load-carrying platform capable of dumping actions. To the damping load-carrying platform, there are connected a partitioning member for partitioning between the load-carrying platform and the passenger's section and the other seat than the driver's seat; and an upper side of the drive unit is opened up in association with a dumping action of the load-carrying platform.
However, with this construction, in order to carry out a maintenance operation of the drive unit disposed under the vehicle body frame, this requires some ingenious arrangement for opening up the upper side of the drive unit, as a matter of course. For this reason, in the case of the conventional technique described above, at a front end position of the dumping platform where the partitioning member is to be attached, there is connected a partitioning member for partitioning from the passenger's section, so that the upper side of the drive unit can be opened up in association with a dumping operation of the load-carrying platform. According to this construction, the upper side of the drive unit disposed downwardly of the vehicle body frame can be opened in association with a dumping operation of the load-carrying platform. Hence, a desired maintenance operation can be carried out advantageously.
However, in the case of this conventional technique, each time there arises the need for maintenance operation, it is needed to open up the upper side of the drive unit by moving the load-carrying platform together with the partitioning member. Therefore, if there is some object or a load loaded on the load-carrying platform, this must be removed. Or, if the situation does not allow displacement of the rear seat, a preliminary operation of e.g. folding this will be needed. And, this preliminary operation would be troublesome. Moreover, during a two rows seat layout mode using both the driver's seat and the rear seat, the dumping operation of the load-carrying platform cannot be carried out.
From the Japanese Patent Application “Kokai” No. 2005-178782 (see paragraph [0018], FIG. 2, FIG. 3 thereof), another work vehicle is known. In this case, the vehicle body frame comprises a rear frame disposed rearwardly at a position higher than the floor face of the passenger's section and a front frame disposed forwardly of the rear frame and adapted for supporting the floor face of the passenger's section. And, an engine and a transmission case are suspended from a support frame downwardly of the rear frame of the vehicle body frame. In this, the layout is such that the positions of the drive unit such as the engine and the transmission case are offset in the fore/aft direction of the vehicle body. With this layout, there is ensured a large space for the upper side of the vehicle body frame, hence, effective utilization of the space over the vehicle body frame is made possible. Further, introduction of ambient air to the radiator can be effected with the entire cooling face of the radiator being opened to the lateral outer side of the vehicle body. Also, as the space under the driver's seat can be utilized as an air exhaust passage, there occurs no interference between the exhaust air from the radiator and the drive unit, so that the exhaust air can flow with low resistance.
However, with the work vehicle according to the Japanese Patent Application “Kokai” No. 2005-178782, if the loading function and the safety performance of the vehicle are to be improved, without significantly changing the size of the entire vehicle body, there arises a problem as follows. That is, if it is desired to increase the number of passengers by modifying the construction on the vehicle body from to one allowing use of both front and rear two rows of seat. this inevitably requires displacement of the position of the rear seat toward the rear side of the vehicle body. However, if the rear seat is provided with such offset arrangement to the rear side of the vehicle body, simple extension, if made, in the length of the vehicle body by an amount corresponding to one row of seat, would be insufficient for ensuring disposing space of the drive unit, etc. This is because, with increase in the loading capacity, it becomes necessary to improve the engine output, which results in turn to increase in the size of the engine per se, and sizes of the transmission case and the peripheral devices and results also in enlargement of the radiator which now has an increased cooling area for providing improved cooling function. And, in the case of the enhancement of the loading capacity and the engine output described above, in order to allow a large radiator to be installed under a transverse posture at the outermost position in the vehicle body width direction while avoiding interference with the rear wheels, the above-described conventional technique would require significant extension in the vehicle body length or extreme enlargement of the wheelbase. Therefore, the technique cannot provide any practical solution. As such, a need exists also for reduction of the cooling load for the radiator and improvement in the scavenging performance for the drive unit, when significant increase in the total vehicle body length is restricted.
Moreover, respecting the ambient air introducing function to the radiator, if the air introducing face having a large width of the radiator is disposed under front facing orientation or a posture approximate thereto, the fore/aft width of the radiator can be reduced, hence being effective for avoiding the increase in the total vehicle body length. In this case; however, the vehicle body or other devices present on the front side of the air introducing face of the radiator would interfere with the air flow, thus creating a new problem of appropriate introduction of ambient air to the entire air introducing face becoming difficult. Conversely, if the wide air introducing face is disposed under the rear facing posture, there is the possibility of occurrence of reverse flow of the exhaust air blown to the front side from the radiator in association with traveling of the vehicle body; hence, this arrangement too is undesirable. As such, a need also exists for appropriate disposing of the enlarged radiator and improvement in the ambient air introducing function for the radiator, when significant increase in the total vehicle body length is restricted.